Diplodia Shoot Blight and Canker
Attacks:
Red, Austrian, Scots, Mugo, White, and Ponderosa pine; Spruce; and Douglas fir
Once the tree is diseased it can never be cured
What you will see:
- Shoot blight phase:
- Brown shoot tips
- Black fruiting bodies (pycnidia) at base of needles and on old cones
- Canker Phase
- Cankers with enormous amounts of sap
- Bleeding cankers
- Gray to black staining of the sapwood
- Black fruiting bodies under bark in the canker
Life cycle:
- Fruiting bodies begin to form in the fall and the following spring on:
- Needles
- Sheaths
- Cone scales
- Bark
- Fungal spores are dispersed by splashing water
- Infection can occur throughout the growing season
- Blights and cankers can both be on the same tree
Cultural practices:
- Enhance Growth
- Reduce stress in environment by reducing or enhancing watering
- Increase tree vigor
- Tree nutrition (Pro-growth or Booster)
- Mulch with low C/N POM
- Root Enhancement System
- Reduce source of inoculum
- Prune affected branches in fall or early spring
- Clean pruning tools between cuts with 5% bleach and 70% alcohol
- Remove fallen limbs
- Rake up and remove dead foliage
Chemical
- Chemicals can manage the blight stage of the disease
- No chemical control is available for the canker stage
- Consult with your Arborist for recommended treatment
Additional Diplodia Shoot Blight and Canker Information:
Infections causing blight and cankers can be incredibly damaging to trees. Diplodia is one such disease, and left untreated, can cause not just destruction, but death of a tree that has been infected. Here’s what you need to know to manage diplodia blight.
Diplodia blight causes shoot blight and branch cankers of pine trees and occasionally other conifers. Cankers can lead to branch death. Repeated infections disfigure trees and may eventually lead to death of the entire tree. Pines with bundles of 2 or 3 needles are more likely to be infected, whereas those with 5 needles per bundle are very resistant. Also, if the tree is growing with stress, then it is more susceptible than those that are already growing nicely. If a tree is near another infected tree, then the danger of diplodia is heightened.
There are several signs of diplodia blight and canker. For one, mature needles will change to a tan color and die off. There is also the possibility of a white substance on dead twigs and branches with cankers present. On dead needles, you may find small black blemishes, which produce spores.
Diplodia spreads through the wind, rain that splashes, gardening tools, animals, and insects. The fungi will lie dormant on infected dead cones and needles on the ground during the winter, and awaken in the spring when it gets more wet and the insects are more prevalent. Even if there is an infection in a developing part of a non-stressed tree, the infection will usually not be able to penetrate the mature, non-stressed branches. For a non-stressed tree to get fully infected, it would need to have an open wound that gets infected.
There are a few ways to manage diplodia. One is that it is best to plant pine trees that are native to the region using local seeds. This means that the trees will be used to the extremes of the weather in the state. Creating a mulch around the tree will mean that you won’t have to mow or trim, which will prevent wounds that could be infected. If you notice diplodia blight or cankers, you can always prune the affected branches to prevent the infection from spreading further.
Watch your trees for the signs of diplodia blight and cankers. If you notice them, make sure to take action quickly.